Plan lush baskets with accurate potting mix needs. Choose shape, units, and liner allowance quickly. Save calculations, reduce waste, and water more efficiently today.
| Example | Shape | Dimensions | Total volume | Usable (90%) |
|---|---|---|---|---|
| A | Round | Ø 30 cm, height 18 cm | 12.72 L | 11.45 L |
| B | Tapered round | Top Ø 35 cm, bottom Ø 20 cm, height 18 cm | 10.96 L | 9.86 L |
| C | Rectangular | 30 × 20 × 16 cm | 9.60 L | 8.64 L |
| D | Half sphere | Ø 28 cm | 5.75 L | 5.17 L |
Hanging baskets dry faster than ground beds, so consistent mix volume matters. A typical 25–35 cm basket often holds about 8–13 L of mix before settling. Using a 90% fill target leaves watering headspace and reduces overflow when you soak the basket thoroughly. For quick conversions, 1 L equals 1,000 cm^3, and 1 US gallon is 3.785 L. If you measure in inches, the calculator converts using 1 inch = 2.54 cm for consistency.
Many “round” baskets are slightly tapered, so the frustum option usually matches reality better than a perfect cylinder. If your top diameter is much larger than the base, frustum volume can be 10–25% lower than a cylinder estimate at the same top size, which helps prevent overbuying. If the rim is slightly oval, measure two directions and average them.
Fill percentage accounts for liner folds, settling, and the space you keep dry at the rim. Common planning values are 85–95%. Drainage space is useful when you keep a bottom void or reserve depth for stones. Subtracting 2 cm from a 16 cm fill height reduces usable volume by about 12.5% in box and round shapes.
Once usable liters are known, bag count becomes a simple division. Rounding up avoids shortages when you top-dress or add extra around root balls. For example, 11.4 L usable volume needs 0.46 of a 25 L bag, while 3 baskets of similar size approach 1.37 bags and should be purchased as 2 bags for comfort.
Wet mix can be heavy, so the optional density input estimates mix mass. If your usable volume is 12 L and density is 0.35 kg/L, mix mass is about 4.2 kg before adding container, plants, and retained water. Always confirm the hook, chain, and bracket rating with a generous safety margin. Many lightweight potting mixes fall around 0.25–0.45 kg/L before watering.
Use the tapered round option. Measure top and bottom diameters inside the liner and the inside height. It usually matches common hanging baskets better than a perfect cylinder.
Start with 90%. Increase to 95% for shallow baskets with little settling. Reduce to 85% if you want extra watering space, use a thick liner fold, or expect strong settling.
If you keep a bottom space that will not be filled with mix, enter that depth as drainage space. If you fully fill with mix and just rely on drainage holes, set it to zero.
A true half-sphere has no flat base height to subtract cleanly. If you reserve space at the bottom, use the fill percentage to reduce usable volume instead of a depth subtraction.
Enter a bag size in liters and the calculator rounds up to whole bags. For multiple baskets, calculate each basket, add usable liters together, then divide by bag size and round up.
No. It estimates mix mass only using your density value. Add container weight, plant mass, and retained water. When unsure, assume higher weight and choose stronger hardware.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.